The invention is based on a hydraulic multi-circuit brake system having an anti-lock and traction control system.
Such a brake system has already been proposed (German Patent Application P 40 34 113.5), in which in the traction control mode, in pressure reduction phases, pressure fluid is let out of the wheel brake of the driven wheel subjected to the excessively high slip, by switching of the outlet valve to the open position. If the vehicle driver effects braking during the traction control mode, and if because of a malfunction the traction control mode is not interrupted, then the brake pressure generated by the driver acts, through the suction line and the charging valve located in it and continuing to occupy its open position, upon the check valve disposed between the high-pressure pump and the storage chamber, and prevents that valve from opening, so that pressure fluid held in the storage chamber is not aspirated by the high-pressure pump, and the storage chamber cannot be evacuated. If the driver then increases the brake pressure, and the brake driven wheel threatens to lock, then with the onset of the anti-lock mode, the rapid brake pressure reduction in the wheel brake may be impaired since the storage chamber is not capable of receiving the pressure fluid flowing out of the wheel brake.